M87.834
BillableOther osteonecrosis of right ulna
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M87.834 an HCC code?
Yes. M87.834 maps to Bone/Joint/Muscle Infections/Necrosis under the CMS-HCC V28 risk adjustment model (and Bone/Joint/Muscle Infections/Necrosis under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for M87.834
For M87.834 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed M87.834 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M87.834 is the ICD-10-CM diagnosis code for other osteonecrosis of right ulna. Death of bone tissue in the right ulna (smaller forearm bone) due to causes other than trauma or infection, leading to bone deterioration and potential collapse. M87.834 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering other osteopathies (m86-m90).
Under the CMS-HCC V28 risk adjustment model, M87.834 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.209. Under the older V24 model, M87.834 mapped to the same category but with a base RAF weight of 0.482 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Distinguish between osteonecrosis of the radius versus ulna, as they are separate codes. Because M87.834 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M87.834 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Distinguish between osteonecrosis of the radius versus ulna, as they are separate codes
- •Document the stage of osteonecrosis if available, as this may influence clinical management
Clinical Significance
Osteonecrosis of the right ulna represents a chronic bone condition affecting the medial forearm bone, potentially compromising elbow and wrist function. This diagnosis has significant risk adjustment implications due to the ongoing orthopedic management requirements and potential for progressive disability.
Documentation Requirements
- ✓Specific identification of the right ulna as the affected bone
- ✓Documentation of osteonecrosis from causes other than idiopathic or drug-induced
- ✓Imaging evidence (MRI, bone scan, CT) confirming ulnar bone necrosis
- ✓Clinical presentation including elbow or forearm pain and functional limitations
- ✓Exclusion of infectious or traumatic causes as primary etiology
- ✓Assessment of impact on arm function and activities of daily living
- ✓Documentation of any contributing risk factors or underlying conditions
- ✓Provider evaluation of treatment options and disease progression
Commonly Confused Codes
- •M87.034 — Idiopathic aseptic necrosis of right ulna - specifically idiopathic etiology
- •M87.036 — Idiopathic aseptic necrosis of unspecified ulna - lacks laterality and different cause
- •M86.834 — Other osteomyelitis, right ulna - infectious bone disease rather than necrosis
- •S52.601A — Unspecified fracture of upper end of right ulna - acute trauma rather than chronic condition
- •M25.521 — Pain in right elbow - symptom code rather than specific bone pathology